package de.fub.bytecode.classfile;

import de.fub.bytecode.Constants;
import java.io.*;
import java.util.*;

/**
 * This class is derived from <em>Attribute</em> and represents a reference to an
 * unknown (i.e. unimplemented) attribute of this class.
 * It is instantiated from the <em>Attribute.readAttribute()</em> method.
 *
 * @version $Id: Unknown.java,v 1.1.1.1 2000/08/10 16:05:07 cvs Exp $
 * @author  <A HREF="http://www.inf.fu-berlin.de/~dahm">M. Dahm</A>
 * @see     Attribute
 */
public final class Unknown extends Attribute {
  private byte[] bytes;
  private String name;

  private static Hashtable unknown_attributes = new Hashtable();

  /**
   * Create a non-standard attribute.
   *
   * @param name_index Index in constant pool
   * @param length Content length in bytes
   * @param bytes Attribute contents
   * @param constant_pool Array of constants
   */
  public Unknown(int name_index, int length, byte[] bytes,
		 ConstantPool constant_pool)
  {
	super(ATTR_UNKNOWN, name_index, length, constant_pool);
	this.bytes = bytes;

	name = ((ConstantUtf8)constant_pool.getConstant(name_index,
						    CONSTANT_Utf8)).getBytes();
	unknown_attributes.put(name, this);
  }  
  /**
   * Construct object from file stream.
   * @param name_index Index in constant pool
   * @param length Content length in bytes
   * @param file Input stream
   * @param constant_pool Array of constants
   * @throw IOException
   */
  Unknown(int name_index, int length, DataInputStream file,
	  ConstantPool constant_pool)
	   throws IOException
  {
	this(name_index, length, (byte [])null, constant_pool);

	if(length > 0) {
	  bytes = new byte[length];
	  file.readFully(bytes);
	}
  }  
  /**
   * Initialize from another object. Note that both objects use the same
   * references (shallow copy). Use clone() for a physical copy.
   */
  public Unknown(Unknown c) {
	this(c.getNameIndex(), c.getLength(), c.getBytes(), c.getConstantPool());
  }  
  /**
   * Called by objects that are traversing the nodes of the tree implicitely
   * defined by the contents of a Java class. I.e., the hierarchy of methods,
   * fields, attributes, etc. spawns a tree of objects.
   *
   * @param v Visitor object
   */
  public void accept(Visitor v) {
	v.visitUnknown(this);
  }  
  /**
   * @return deep copy of this attribute
   */
  public Attribute copy(ConstantPool constant_pool) {
	Unknown c = (Unknown)clone();

	if(bytes != null)
	  c.bytes = (byte[])bytes.clone();

	c.constant_pool = constant_pool;
	return c;
  }  
  /**
   * Dump unknown bytes to file stream.
   *
   * @param file Output file stream
   * @throw IOException
   */ 
  public final void dump(DataOutputStream file) throws IOException
  {
	super.dump(file);
	if(length > 0)
	  file.write(bytes, 0, length);
  }  
  /**
   * @return data bytes.
   */  
  public final byte[] getBytes() { return bytes; }  
  /**
   * @return name of attribute.
   */  
  public final String getName() { return name; }  
  /** @return array of unknown attributes, but just one for each kind.
   */
  static Unknown[] getUnknownAttributes() {
	Unknown[]   unknowns = new Unknown[unknown_attributes.size()];
	Enumeration entries  = unknown_attributes.elements();

	for(int i=0; entries.hasMoreElements(); i++)
	  unknowns[i] = (Unknown)entries.nextElement();

	unknown_attributes = new Hashtable();
	return unknowns;
  }  
  /**
   * @param bytes.
   */
  public final void setBytes(byte[] bytes) {
	this.bytes = bytes;
  }  
  /**
   * @return String representation.
   */ 
  public final String toString() {
	if(length == 0 || bytes == null)
	  return "(Unknown attribute " + name + ")";

	String hex;
	if(length > 10) {
	  byte[] tmp = new byte[10];
	  System.arraycopy(bytes, 0, tmp, 0, 10);
	  hex = Utility.toHexString(tmp) + "... (truncated)";
	}
	else
	  hex = Utility.toHexString(bytes);

	return "(Unknown attribute " + name + ": " + hex + ")";
  }  
}